Rotary switch with improved contact structure and camming means



Jan. 17, 1967 c, w, HEATH 3,299,225

ROTARY SWITCH WITH IMPROVED CONTACT STRUCTURE AND CAMMING MEANS FiledMarch 9, 1966 INVENTOR CLfiRE/VCE W/Lm/vs hEHTH.

ATTORNEY United States Patent 3,299,225 ROTARY SWITCH WITH IMPROVEDCONTACT STRUCTURE AND CAMMING MEANS Clarence Willans Heath, Bleasby,England, assignor to United-Carr Incorporated, Boston, Mass., acorporation of Delaware Filed Mar. 9, 1966, Ser. No. 532,997 Claimspriority, application Great Britain, Mar. 31, 1965, 13 637 2 Claims.(Cl. 2006) This invention relates to a rotary switch comprising amovable contact arm adapted to be moved relative to a fixed contact by arotor.

According to the present invention, a rotary electrical switch comprisesa rotatable cam, at least one pivotally mounted contact carrying armengageable by the cam so as to be displaced thereby into and out ofengagement with a fixed contact, resilient means being provided engagingthe arm adjacent to its pivot so as to resiliently urge the arm againstthe cam.

A pair of opposed fixed contacts may be provided, the contact on themovable arm being movable under the control of the cam into engagementwith each of the fixed contacts or into an intermediate position out ofengagement with both said contacts.

The cam may be adapted to engage an intermediate portion of the arm.

Preferably the resilient means comprises a spring engageable with thearm adjacent to its pivotally mounted end.

To enable the invention to be fully understood, it will now bedescribed, by way of example, with reference to the accompanying drawingwhich schematically illustrates a rotary switch according to oneembodiment of the invention.

As shown in the said drawing, the switch comprises a casing 1 and acover 2 in which are mounted fixed contacts 3, 3a, 4, 4a, the portionsof the contacts projecting into the casing being provided with contactpips b. AS shown, the pips b of the contacts 3, 3a as also those of thecontacts 4, 4a, are in opposed facing relation.

Movable contact arms 5, 6 are provided having double faced contact pips5a, 6a at one end. At the opposite end the respective arms are formedwith lugs 7, 8, pivotally supported in slots 9 in contact members 10.Each of the contact arms is provided with resilient means urging ittowards the cam surface 11 of a rotor 12. As shown, each resilient meanscomprises a coil spring 13 housed in a shroud 14 of rubber or otherflexible insulating material and formed with a projection 15 at one endextending into an aperture in the respective contact arms adjacent tothe pivotal mounting thereon. The springs 13 normally tend to extend theshrouds so as resiliently to urge the contact arms towards the camsurface 11 so that the ar-cuately bent portions 16 of the respectivearms are maintained in contact with the cam surface 11 as the rotorrotates.

The contact members are formed with tailpieces 17 projecting outwardlyof the switch casing for connection to lead wires to complete a circuitto the respective arms 5 and 6. It will be noted that the shrouds 14insulate the contact arms from the springs 13.

The fixed contacts 3, 3a, 4, 4a are also adapted to be attached to leadwires, and accordingly during the rotation of the rotor 12, when thehigh portions of the cam 11 engages the portions 16 of the arms 5 and 6respectively, they will be displaced against the action of theirrespective springs 13 into engagement with the fixed contacts 3, and 4.When the recessed or low portion of the cam is aligned with the portion16, the arms will be positioned in engagement with the fixed contacts3a, 4a, and when the portion of the cam intermediate the high andrecessed portion is aligned with the bent portion 15, the contact armswill be in an intermediate position out of engagement with both thefixed contacts.

The springs 13 not only serve to urge the arms into resilient engagementwith the cam surface 11 of the rotor, but also serve to absorb anypressure exerted on the contact arms in excess of that necessary toeffect the efficient electrical engagement of the pips of the arms 5, 6with the pips of the fixed contacts.

It will be understood that if the pressure is excessive, there would bea tendency for the contact arms 5 and 6 to be overstressed mechanicallyso as to cause them to break or assume a set which will impair theefiicient operation of the switch.

While the switch illustrated and described is provided with two movablecontacts each engageable with two fixed contacts, it will be understoodthat the switch may include one, or more than two movable contacts, eachengageable with a single or a pair of contacts.

I claim:

1. A rotary electrical switch comprising a rotatable cam, mounted in acasing, at least one contact arm pivotally mounted, at one end, in saidcasing, the opposite end being provided with an electrical contact forengagement with a fixed contact, said contact arm engageable by said camso as to be displaceable thereby to position said electrical contactinto and out of engagement with said fixed electrical contact, springmeans enclosed in a flexible housing of insulating material providedadjacent the pivot end of said arm to urge an intermediate portion ofsaid arm into engagement with said cam, the action of said spring meansbeing transmitted through said housing to said arm.

2. A rotary electrical switch as set forth in claim 1 wherein saidcontact arm has an aperture formed therethrough in close proximity tosaid pivotal end and said spring means has means engaged in saidaperture formed in said contact arm.

References Cited by the Examiner UNITED STATES PATENTS 2,262,306 11/1941 Thompson 2006 2,832,851 4/1958 Jones 2006 3,241,381 3/1966 Kuhn etal 74-97 ROBERT K. SCHAEFER, Primary Examiner. J. SCOTT, AssistantExaminer.

1. A ROTARY ELECTRICAL SWITCH COMPRISING A ROTATABLE CAM, MOUNTED IN ACASING, AT LEAST ONE CONTACT ARM PIVOTALLY MOUNTED, AT ONE END, IN SAIDCASING, THE OPPOSITE END BEING PROVIDED WITH AN ELECTRICAL CONTACT FORENGAGEMENT WITH A FIXED CONTACT, SAID CONTACT ARM ENGAGEABLE BY SAID CAMSO AS TO BE DISPLACEABLE THEREBY TO POSITION SAID ELECTRICAL CONTACTINTO AND OUT OF ENGAGEMENT WITH SAID FIXED ELECTRICAL CONTACT, SPRINGMEANS ENCLOSED IN A FLEXIBLE HOUSING OF INSULATING MATERIAL PROVIDEDADJACENT THE PIVOT END OF SAID ARM TO URGE AN INTERMEDIATE PORTION OFSAID ARM INTO ENGAGEMENT WITH SAID CAM, THE ACTION OF SAID SPRING MEANSBEING TRANSMITTED THROUGH SAID HOUSING TO SAID ARM.